1. Field of the Invention
The present invention relates to an image processing apparatus for converting a color region in an input color image into a predetermined image corresponding to the color.
2. Related Background Art
Conventionally, a facsimile apparatus capable of identifying a plurality of colors from each other, and reading these colors, transmits color information if a receiving facsimile apparatus can record a plurality of colors. However, if a receiving facsimile apparatus can only record a single color (e.g., black) (to be referred to as a monochrome facsimile apparatus hereinafter), the facsimile apparatus transmits binary information reflecting only the lightness of the read color information.
For this reason, when color original information is transmitted to a monochrome facsimile apparatus, the receiving apparatus cannot identify colors even though the transmitting apparatus faithfully reads a color image on a color original.
For example, assume that a color original, on which an upper circular graph is classified by five colors, i.e., red, blue, green, pink, and yellow, the five colors used in the circular graph are actually presented in a lower comment portion, and item names (product names in this case) corresponding to these colors are added to the colors, as shown in FIG. 8, is transmitted to a monochrome facsimile apparatus. In the case of the color original shown in FIG. 8, the receiving apparatus records red, blue, and green as black since they have low lightness, and records pink and yellow as white since they have high lightness, as shown in, e.g., FIG. 9. Therefore, although a group of red, blue, and green, and a group of pink and yellow can be discriminated from each other, red, blue and green, and pink and yellow in these groups cannot be distinguished from each other. As a result, information of the circular graph cannot be correctly recognized.
When the color original shown in FIG. 8 is transmitted to the monochrome facsimile apparatus in a halftone mode, since the same color information in the circular graph and the comment of the graph is recorded by a single tone pattern, the correspondence between the circular graph and the comment portion can be read, and information of the circular graph may be correctly recognized.
However, when a color original, on which the comment of the graph in FIG. 8 is made by a text, as shown in FIG. 11, is transmitted in the halftone mode, the receiving apparatus records the information, as shown in FIG. 12. For this reason, even when the comment text includes color names, the correspondence between the colors and the tone patterns in the circular graph cannot be determined, and information of the circular graph cannot be correctly recognized.
The above-mentioned problems occur not only when color information is transmitted to a monochrome facsimile apparatus but also when a facsimile apparatus which can read seven colors, i.e., black, red, blue, green, pink, yellow, and purple transmits information including blue, green, pink, yellow, and purple to a facsimile apparatus which can record two colors, i.e., black and white.